Annular relief valve

ABSTRACT

A pressure relief valve assembly may be coupled to one or more casings and/or tubular members to control fluid communication therebetween. In one embodiment, the valve assembly includes a tubular body having a port for fluid communication between an exterior of the tubular body and an interior of the tubular body; a chamber formed in a wall of the tubular body, the chamber in fluid communication with the port; a closure member disposed in the chamber and configured to control fluid communication through the port in response to a pressure differential; and a retaining member coupled to the closure member for retaining the closure member in an open position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent Application Ser. No. 61/880,690, filed Sep. 20, 2013, which application is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention generally relate to a pressure relief valve assembly for a casing.

2. Description of the Related Art

Traditional well construction, such as the drilling of an oil or gas well, includes a wellbore or borehole being drilled through a series of formations. Each formation, through which the well passes, must be sealed so as to avoid an undesirable passage of formation fluids, gases or materials out of the formation and into the borehole. Conventional well architecture includes cementing casings in the borehole to isolate or seal each formation. The casings prevent the collapse of the borehole wall and prevent the undesired inflow of fluids from the formation into the borehole.

In standard practice, each succeeding casing placed in the wellbore has an outside diameter significantly reduced in size when compared to the casing previously installed. The borehole is drilled in intervals whereby a casing, which is to be installed in a lower borehole interval, is lowered through a previously installed casing of an upper borehole interval and then cemented in the borehole. The purpose of the cement around the casing is to fix the casing in the well and to seal the borehole around the casing in order to prevent vertical flow of fluid alongside the casing towards other formation layers or even to the earth's surface.

If the cement seal is breached, due to high pressure in the formations and/or poor bonding in the cement for example, fluids (liquid or gas) may begin to migrate up the borehole. The fluids may flow into the annuli between previously installed casings and cause undesirable pressure differentials across the casings. The fluid gas may also flow into the annuli between the casings and other drilling or production tubular members that are disposed in the borehole. Some of the casings and other tubulars, such as the larger diameter casings, may not be rated to handle the unexpected pressure increases, which can result in the collapse or burst of a casing or tubular.

Therefore, there is a need for apparatus and methods to prevent wellbore casing or tubular failure due to unexpected downhole pressure changes.

SUMMARY OF THE INVENTION

A pressure relief valve assembly may be coupled to one or more casings and/or tubular members to control fluid communication therebetween. The valve assembly is a one-way valve assembly that relieves pressure within an annulus formed between adjacent casings and/or tubular members to prevent burst or collapse of the casings and/or tubular members. In one embodiment, the valve assembly includes a tubular body having a port for fluid communication between an exterior of the valve assembly and an interior of the valve assembly; a chamber formed in a wall of the tubular body, the chamber in fluid communication with the port; a closure member disposed in the chamber and configured to control fluid communication through the port in response to a pressure differential; and a retaining member coupled to the closure member for retaining the closure member in an open position.

In another embodiment, the valve assembly includes a biasing member for biasing the closure member in a closed position. The valve assembly may include a plug disposed on an end opposite the closure member. In one aspect, the activation force of the closure member is adjustable. The activation force may be adjusted by changing a location of the plug. In another embodiment, the activation force may be adjusted by changing a length of the piston.

In another embodiment, a method of operating a valve assembly includes coupling a valve assembly to a casing and the valve assembly having a tubular body having a port for fluid communication between an exterior of the valve assembly and an interior of the valve assembly; a chamber formed in a wall of the tubular body, the chamber in fluid communication with the port; a closure member disposed in the chamber and configured to control fluid communication through the port; and a retaining member coupled to the closure member for retaining the closure member in an open position. The method further includes opening the valve assembly in response to a predetermined pressure differential between the exterior and the interior of the valve assembly, and retaining the closure member in the open position.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

FIG. 1 is a schematic view of a wellbore.

FIG. 2 illustrates an exemplary embodiment of a valve assembly. FIG. 2A is a longitudinal cross-sectional view of a tubular body containing the valve assembly.

FIG. 3 is an enlarged cross-sectional view of the valve assembly of FIG. 2 in the closed position.

FIG. 4 is an enlarged cross-sectional view of the valve assembly of FIG. 2 in the open position.

FIG. 5 is a cross-sectional view of another embodiment of a valve assembly in the closed position. FIG. 5A is an enlarged, partial cross-sectional view of the valve assembly of FIG. 5.

FIG. 6 is a cross-sectional view of another embodiment of a valve assembly in the open position. FIG. 6A is an enlarged, partial cross-sectional view of the valve assembly of FIG. 6.

FIG. 7 illustrates an exemplary embodiment of a closure member.

FIG. 8 illustrates another exemplary embodiment of a closure member.

DETAILED DESCRIPTION

In one embodiment, a pressure relief valve assembly may be coupled to one or more casings and/or tubular members to control fluid communication there between. The valve assembly is a one-way valve assembly that relieves pressure within an annulus formed between adjacent casings and/or tubular members to prevent burst or collapse of the casings and/or tubular members. The valve assembly may be resettable downhole.

FIG. 1 illustrates a wellbore 5 formed within an earthen formation 80. The walls of the wellbore 5 are reinforced with a plurality of casings 10, 20, 30 of varying diameters that are structurally supported within the formation 80. The casings 10, 20, 30 are fixed within the formation 80 using a sealing material 15, 25, 35, such as cement, which prevents the migration of fluids from the formation 80 into the annuli between the casings 10, 20, 30. One or more tubular members 40, 45, such as drilling or production tubular members, may also be disposed in the wellbore 5 for conducting wellbore operations. An annulus “A” is formed between the casing 10 and the casing 20, and an annulus “B” is formed between the casing 20 and the tubular member 40, which may also be a casing. It is important to note that the embodiments described herein may be used with other wellbore arrangements and are not limited to use with the wellbore configuration illustrated in FIG. 1.

The wellbore 5 may intersect a high pressure zone 50 within the formation 80. Fluids within the high pressure zone 50 are sealed from the annulus A and B by the sealing material 25 that is disposed between the casing 20 and the wellbore wall. In the event that the sealing material 25 is breached or otherwise compromised, pressurized fluids may migrate upward into the annulus A and cause an unexpected pressure increase. The pressure rise may form a pressure differential across the casings 10, 20 that, if unchecked, may result in leakage through or burst of casing 10, and/or leakage through or collapse of casing 20. One or more valve assemblies 300, 700 are provided to relieve the pressure in the annulus A prior to failure of one or both of the casings 10, 20.

FIG. 2 illustrates an exemplary embodiment of a valve assembly 700 for relieving pressure in annulus A to prevent failure of the casings 10, 20. The valve assembly 700 may be coupled to the casing 20 in FIG. 1, but each of the casings 10, 20, 30 and/or the tubular members 40, 45 may similarly include one or more of the valve assembly 700 as described herein. The valve assembly 700 may be coupled to the casings 10, 20, 30 and/or the tubular members 40, 45 using a thread connection, a welded connection, and/or other similar connection arrangements. The valve assembly 700 may also be integral with the casings.

FIG. 2 is a cross-sectional view of an exemplary valve assembly 700 positioned in a wall of a tubular body 705. FIG. 2A is a longitudinal cross-sectional view of the tubular body 705 containing the valve assembly 700. The tubular body 705 has an axial bore 701 formed therethrough and may include threads for connection to a tubular such as casing 20. In another embodiment, the tubular body may be integral with the casing. In yet another embodiment, the valve assembly 700 may be disposed in an enlarged section of a tubular body.

FIGS. 3 and 4 are enlarged cross-sectional views of the valve assembly 700 in the closed position and the open position, respectively. The tubular body 705 has a relief port 715 formed through the wall of the body 705 for selective fluid communication between an exterior of the casing 20 and an interior of the casing 20. In another embodiment, the body 705 may include a plurality of valve assemblies circumferentially spaced around the body 705. Additionally, the body 705 may include multiple valve assemblies disposed at different locations along the length of the body 705. Valve assemblies disposed at different axial locations on the body 705 may reduce the effect the valve assemblies have on the integrity, e.g., tensile strength, of the valve body 705. In yet another embodiment, the valve assemblies may be positioned in an enlarged, concentric or eccentric section of the tubular body. Placement of the valve assembly in the enlarged cross section of the concentric or eccentric section may offset the effects on tensile strength, burst resistance, and collapse resistance on the body.

The tubular body 705 includes a chamber 713 for housing a closure member 720. The closure member 720 is used to operate the relief port 715. An exemplary closure member is a piston 720. In one embodiment, the piston 720 includes a first portion 721 having a smaller diameter than a second portion 722. A seal 731, 732 is disposed around each of the first and second portions 721, 722 of the piston 720 for sealing engagement with the chamber 713. An exemplary seal is an o-ring. The piston 720 is movably disposed in the chamber 713 to operate the valve. As shown, the piston 720 is biased in the closed position using a biasing member 735. Exemplary biasing members 735 include a coil spring or a wave spring. The biasing member 735 may be configured to retract in response to a force near or below the burst or collapse rating of the casing 20. One or more plugs may optionally be used to enclose the chamber 713. In the embodiment as shown, three plugs 727, 728 are used to close off openings in the tubular body 705 formed during manufacture of the valve assembly 700. The plugs 727, 728 may optionally include a seal 726, a retaining ring 729, or both.

In one embodiment, the chamber 713 can fluidly communicate with the relief port 715 and a chamber port 719 of the body 705. The relief port 715 allows fluid communication between the bore 701 and the portion 741 of the chamber 713 defined by the first seal 731. The chamber port 719 allows fluid communication between the bore 701 and the portion 742 of the chamber 713 defined by the second seal 732. An inflow port 718 and an actuation port 745 allow fluid communication between the exterior of the tubular body 705 and the portion 743 of the chamber 713 between the first seal 731 and the second seal 732. In this respect, these ports 718, 745 are blocked from fluid communication with the bore by the closure member 720 when the valve assembly 700 is in the closed position. The inflow port 718 and the actuation port 745 are positioned such that in the open position, the inflow port 718 is allowed to communicate with the relief port 715, and the actuation port 745 remains blocked from communication with the bore 701.

Referring back to FIG. 1, the valve assembly 700 may be operable to control fluid communication between the annulus A and the annulus B. The annulus A surrounds the valve assembly 700, and the annulus B is in fluid communication with the bore 701 of the valve assembly 700.

FIG. 3 shows the valve assembly 700 in the closed position. During operation, the biasing member 735 and the pressure in annulus B are acting on the piston 720 to keep the valve assembly closed. The pressure in annulus B is acting on both sides of the piston 720 via the relief port 715 and the chamber port 719. Because the second portion 722 of the piston 720 has a larger diameter than the first portion 721, the pressure in annulus B has an overall effect of urging piston 720 to the closed position. The pressure in annulus A may act on the piston 720 via the actuation port 745. The annulus A pressure acts on a tapered section of the piston 720 where the diameter changes to urge the piston 720 toward the open position.

When the pressure in annulus A is sufficient to overcome the biasing force and the force from the annulus B pressure, the piston 720 is retracted to open the inflow port 718 and place the inflow port 718 in fluid communication with the relief port 715. FIG. 4 shows the valve assembly 700 in the open position. As shown, the piston 720 has moved to a position where the first seal 731 is disposed between the actuation port 745 and the inflow port 718. Pressurized fluid may flow from the annulus A to the annulus B through the inflow port 718, the chamber 713, and the relief port 715 of the valve assembly 700. Fluid from the actuation port 745 is blocked from communication with the relief port 715 by the first seal 731. The valve assembly 700 is thus operable to relieve and prevent any pressure differential that may cause burst or collapse of the casings 10, 20.

When the force on piston 720 due to pressure in the annulus A decreases below the sum of the force on piston 720 due to pressure in annulus B plus the biasing force of the biasing member 735, the biasing member 735 returns the piston 720 to the closed position, thereby closing off fluid communication through the relief port 715. In this manner, the valve assembly 700 is operable as a one-way valve in that it will permit fluid flow into the bore 701 of the valve assembly 700 but will prevent fluid flow out of the bore 701 via the relief port 715. The valve assembly 700 is automatically resettable downhole and may be operated multiple times in response to any pressure fluctuations within the wellbore 5. As stated above, any of the casings 10, 20, 30 and/or the tubular members 40, 45 may each be provided with one or more valve assemblies 700 to allow fluid flow from a surrounding casing or tubular member to an inner casing or tubular member, while preventing fluid flow in the opposite direction.

FIGS. 5 and 6 are cross-sectional views of another exemplary embodiment of a valve assembly 300 positioned in a wall of a tubular body 305. FIG. 5 shows the valve assembly 300 in the closed position, and FIG. 6 shows the valve assembly 300 in the open position. FIGS. 5A and 6A are enlarged, partial views of FIGS. 5 and 6, respectively. The tubular body 305 may be the tubular body 705 shown in FIG. 2A. The tubular body 305 has an axial bore 301 formed therethrough and may include threads for connection to a tubular such as casing 20. In another embodiment, the tubular body 305 may be integral with the casing 20. In yet another embodiment, the valve assembly 300 may be disposed in an enlarged section of a tubular body 305.

Referring to FIGS. 5 and 5A, the tubular body 305 has a relief port 315 formed through the wall of the body 305 for selective fluid communication between an exterior of the body 305 and an interior of the body 305. In another embodiment, the body 305 may include a plurality of valve assemblies circumferentially spaced around the body 305. Additionally, the body 305 may include multiple valve assemblies disposed at different locations along the length of the body 305. Valve assemblies disposed at different axial locations on the body 305 may reduce the effect the valve assemblies have on the integrity, e.g., tensile strength, of the valve body 305. In yet another embodiment, the valve assemblies may be positioned in an enlarged, concentric or eccentric section of the tubular body. Placement of the valve assembly in the enlarged cross section of the concentric or eccentric section may offset the effects on tensile strength, burst resistance, and collapse resistance on the body.

The tubular body 305 includes a chamber 313 for housing a closure member 320. The chamber 313 is in fluid communication with the bore 301 via the relief port 315 and a chamber port 319. Also, the chamber 313 is in selective fluid communication with the exterior of the tubular body 305 via an inflow port 318. In one embodiment, the chamber 313 may include a shoulder 344 disposed between a smaller diameter section 311 of the chamber 313 and a larger diameter section 312 of the chamber 313.

The closure member 320 is used to selectively control fluid communication between the relief port 315 and the inflow port 318. An exemplary closure member is a piston 320. In one embodiment, as shown in FIG. 5A, the piston 320 includes a body portion 321, a head portion 322, a retaining member 323, and a base portion 324. The body portion 321 may include a stem coupled to the head portion 322. The head portion 322 is configured to block fluid communication through the inflow port 318. In one embodiment, the inflow port 318 has a smaller diameter than the smaller diameter section 311 of the chamber 313. In this embodiment, the head portion 322 may include a smaller diameter nose section configured to seal the inflow port 318. A sealing member 332 is disposed around the nose section for sealingly engaging the inner surface of the inflow port 318. It is contemplated that the head portion 322 may take on any suitable shape so long as the head portion 322 is adapted to block fluid communication between the inflow port 318 and the relief port 315. The body portion 321 may be configured to be at least partially disposed in the smaller diameter section of the chamber 313. The base portion 324 is coupled to the other end of the body portion 321 and is adapted to engage a biasing member 335. A sealing member 331 is disposed between the body portion 321 and the base portion 324 and is configured to sealingly engage the chamber 313. Exemplary sealing member 331, 332 is an o-ring. Although the piston 320 is described as having multiple portions, it is contemplated that one or more of the portions may be integrated with each other. For example, the head portion 322 and the body portion 321 may form a single body portion. The portions of the piston 320 may be connected using threads, interference fit, and other suitable connection mechanisms. The base portion 324 may optionally include a retrieval receptacle for receiving a retrieval tool to facilitate removal of the piston 320 from the chamber 313.

The retaining member 323 is coupled to the head portion 322 and is configured to retain the piston 320 in the open position. In one embodiment, the retaining member is a collet 323. The collet 323 may extend along the stem of the body portion 321 and may flex radially inwardly and outwardly. As shown in FIG. 5A, the collet 323 is flexed inwardly due to being positioned in the smaller diameter section 311 of the chamber 313. The collet 323 flex outwardly when it is in the larger diameter section 312 of the chamber 313, as shown in FIG. 6A. The collet 323 may help resist retraction of the piston 320.

Referring back to FIG. 5, the piston 320 is movably disposed in the chamber 313 to operate the valve 300. As shown, the piston 320 is biased in the closed position using a biasing member 335. Exemplary biasing members 335 include a coil spring or a wave spring. The biasing member 335 may be configured to retract in response to a force near or below the collapse rating of the casing 20.

A plug 328 is provided to engage the other end of the biasing member 335 and to enclose the chamber 313. The plug 328 is disposed in an opening 375 of the tubular body 305 that leads to the chamber 313. As shown, the opening 375 has a larger diameter than the chamber 313, thereby forming a shoulder 376 at the interface. In another embodiment, the opening 375 may have the same or different diameter than the chamber 313. The plug 328 may optionally include a seal 326 to prevent communication through the opening 375. The plug 328 may include a recess for receiving the seal 326. The plug 328 may separate into a front section and a body section at the recess to facilitate installation of the seal 326. The two sections may be connected using threads, interference fit, and other suitable connection mechanisms. The front section may include an outer diameter of sufficient size to engage the shoulder 376. The plug 328 may optionally include a retrieval receptacle for receiving a retrieval tool to facilitate removal of the plug 328 from the opening 375. In another embodiment, the body section may include threads for attachment to the opening 375. In addition to threads, it is contemplated that the plug 328 may attach to the opening 375 using an interference fit, a locking mechanism such as a pin or screw, or any suitable attachment mechanism.

In one embodiment, the valve assembly 300 includes an adjustable activation pressure feature. Referring again to FIGS. 5 and 5A, the opening force may be adjusted by changing the distance between the plug 328 and the piston 320 in the closed position. The change in distance, in turn, changes the force required to compress the biasing member 335, thereby retracting the piston 320 to the open position. In one embodiment, the plug 328 is threadedly connected to the opening 375. The threads allow adjustment of the distance between the plug 328 and the piston 320. In another embodiment, the distance may be changed by adjusting the length of the stem of the body portion 321.

Referring to FIG. 5, the chamber 313 can fluidly communicate with the relief port 315 and the chamber port 319 of the tubular body 305. The relief port 315 allows fluid communication between the bore 301 and the portion of the chamber 313 between seals 331, 332 of the piston 320. The chamber port 319 allows fluid communication between the bore 301 and the portion of the chamber 313 defined by the first seal 331 and the plug 328. The inflow port 318 allows selective fluid communication between the exterior of the tubular body 305 and the interior of the tubular body 305. The inflow port 318 is blocked from fluid communication with the bore 301 by the closure member 320 when the valve assembly 300 is in the closed position.

Referring back to FIG. 1, the valve assembly 300 may be operable to control fluid communication between the annulus A and the annulus B. The annulus A surrounds the valve assembly 300, and the annulus B (i.e., the interior of the tubular body 305) is in fluid communication with the bore 301 of the valve assembly 300.

FIG. 5 shows the valve assembly 300 in the closed position. During operation, the biasing member 335 and the pressure in annulus B are acting on the piston 320 to keep the valve assembly 300 closed. The pressure in annulus B is acting on both sides of the first seal 331 of the piston 320 via the relief port 315 and the chamber port 319. The pressure in annulus B is also acting on the interior side of the second seal 332. The pressure in annulus A may act on the front of the piston 320 via the inflow port 318 to urge the piston 320 toward the open position.

When the pressure in annulus A is sufficient to overcome the biasing force of the biasing member 335 and the force from the annulus B pressure, the piston 320 is retracted to open the inflow port 318 and place the inflow port 318 in fluid communication with the relief port 315. FIGS. 6 and 6A show the valve assembly 300 in the open position. In one embodiment, the activation force required to open the inflow port 318 is set below the collapse pressure of the casing 20. As shown, the piston 320 has moved to a position where pressurized fluid is allowed to flow from annulus A to annulus B through the inflow port 318, the chamber 313, and the relief port 315 of the valve assembly 300. Also, the collet 323 has moved to the larger diameter section of the chamber 313, whereby the collet 323 is allowed to flex outward to engage the shoulder 344. In this respect, the collet 323 helps maintain the piston 320 in the open position. The valve assembly 300 is thus operable to relieve and prevent any pressure differential that may cause collapse of the casings 10, 20.

The relief port 315 is closed when the net force acting on the piston 320 (due to pressure differential between annulus A and annulus B and to the spring force) decreases to a threshold closing force sufficient to release the collet 323, which in turn, returns the piston 320 to the closed position. Because the collet 323 helps to retain the piston 320 in the open position, the pressure differential between annulus A and annulus B required to close the port 315 is smaller than the pressure differential required to open the port 315. If the pressure in annulus A decreases, the port 315 will remain open as long as the pressure differential is greater than the closing pressure differential. In this manner, the valve assembly 300 is operable as a one-way valve that permits fluid flow into the bore 301 of the valve assembly 300 but prevents fluid flow out of the bore 301 via the relief port 315. The valve assembly 300 is automatically resettable downhole and may be operated multiple times in response to pressure fluctuations within the wellbore 5. As stated above, any of the casings 10, 20, 30 and/or the tubular members 40, 45 may each be provided with one or more valve assemblies 300 to allow fluid flow from a surrounding casing or tubular member to an inner casing or tubular member, while preventing fluid flow in the opposite direction.

FIG. 7 illustrates another embodiment of a closure member 420. The closure member 420 is suitable for use with the valve 300 of FIG. 5. In this embodiment, the closure member is a piston 420. As shown, the piston 420 includes a head portion 422, a body portion 421, and a base portion 424 that are integrated as a single body 421. In another embodiment, the portions 421, 422, 424 may be made of two or more connected portions. The piston 420 also includes a retaining member 423 disposed around the body portion 421. The head portion 422 is configured to block fluid communication through the inflow port 318. In this embodiment, the head portion 422 may include a smaller diameter nose section configured to seal the inflow port 318. A sealing member 432 is disposed around the nose section for sealingly engaging the inner surface of the inflow port 318. It is contemplated that the head portion 422 may take on any suitable shape so long as the head portion 422 is adapted to block fluid communication between the inflow port 318 and the relief port 315. The body portion 421 may be configured to be at least partially disposed in the smaller diameter section 311 of the chamber 313. The base portion 424 is adapted to engage a biasing member 335. A sealing member 431 is disposed around the base portion 424 and is configured to sealingly engage the chamber 313. Exemplary sealing member 431, 432 is an o-ring. The base portion 424 may optionally include a retrieval receptacle for receiving a retrieval tool to facilitate removal of the piston 420 from the chamber 313.

The retaining member 423 is coupled to the body portion 421 and is configured to retain the piston 420 in the open position. In this embodiment, the retaining member is an o-ring 423 that may be disposed in a recess in the body portion 421. The o-ring 423 is compressed when disposed in the smaller diameter section of the chamber 313. When the piston 420 is retracted to open the inflow port 318, the o-ring 423 is moved to the larger diameter section 312 of the chamber 313, whereby the o-ring is allowed to expand outward to engage the shoulder 344. In this respect, the o-ring 423 can help maintain the piston 420 in the open position. The relief port 315 is closed when the forces acting on the piston 320 due to pressure differential between annulus A and annulus B and to the spring force decreases to a threshold closing force sufficient to compress the o-ring 423 sufficiently to allow the o-ring 423 to move into the smaller diameter section of the chamber 313.

FIG. 8 illustrates another embodiment of a closure member 520. The closure member 520 is suitable for use with the valve 300 of FIG. 5. In this embodiment, the closure member is a piston 520. As shown, the piston 520 includes a head portion 522, a body portion 521, and a base portion 524 that are integrated as a single body 521. In another embodiment, the portions 521, 522, 524 may be made of two or more connected portions. The piston 520 also includes a retaining member 523 disposed around the body portion 521. The head portion 522 is configured to block fluid communication through the inflow port 318. In this embodiment, the head portion 522 may include a smaller diameter nose section configured to seal the inflow port 318. A sealing member 532 is disposed around the nose section for sealingly engaging the inner surface of the inflow port 318. It is contemplated that the head portion 522 may take on any suitable shape so long as the head portion 522 is adapted to block fluid communication between the inflow port 318 and the relief port 315. The body portion 521 may be configured to be at least partially disposed in the smaller diameter section of the chamber 313. The base portion 524 is adapted to engage a biasing member 335. A sealing member 531 is disposed around the base portion 524 and is configured to sealingly engage the chamber 313. Exemplary sealing member 531, 532 is an o-ring. The base portion 524 may optionally include a retrieval receptacle for receiving a retrieval tool to facilitate removal of the piston 520 from the chamber 313.

The retaining member 523 is coupled to the body portion 521 and is configured to assist with retaining the piston 520 in the open position. In this embodiment, the retaining member is a snap ring 523 that is disposed in a recess in the body portion 521. The snap ring 523 is compressed when disposed in the smaller diameter section 311 of the chamber 313. When the piston 520 is retracted to open the inflow port 318, the snap ring 523 is moved to the larger diameter section 312 of the chamber 313, whereby the snap ring 523 is allowed to expand outward to engage the shoulder 344. In this respect, the snap ring 523 can help maintain the piston 520 in the open position. The relief port 315 is closed when the forces acting on the piston 320 due to pressure differential between annulus A and annulus B and to the spring force decreases to a threshold closing force sufficient to compress the snap ring 523 sufficiently to allow the snap ring 523 to move into the smaller diameter section of the chamber 313.

In yet another embodiment, the valve assembly 700 of FIG. 3 may be equipped with a retaining member as described herein, including a collet, an o-ring, or a snap ring. The retaining member may be used to retain the closure member 720 in the open position. In this respect, the pressure differential needed to close the valve assembly 700 must be sufficient to release the retaining member before the closure member 720 is allowed to close.

In any of the embodiments described herein, any of the casings 10, 20, 30 and/or the tubular members 40, 45 may each be provided with one or more valve assemblies 300 and 700 to allow fluid flow from a surrounding casing or tubular member to an inner casing or tubular member, while preventing fluid flow in the opposite direction. In one embodiment, a casing or tubular member may be provided with multiple valve assemblies that are spaced apart along the length of the casing or tubular member. The valve assemblies 300 and 700 may be operable to open and/or close at different pre-determined pressure setting.

Embodiments of the valve assemblies 300 and 700 may be used to prevent collapse of a casing. For example, during an uncontrolled flow situation such as a catastrophic blowout, the hot hydrocarbon fluids from lower portions of the well may heat the fluid which is trapped in the annular space between an outer casing and an inner casing. The annular space may extend from top of the cement level to liner hanger. If the inner casing extends to the surface, then the annul area may extend from the top of the cement level and up to the surface. When the trapped fluid in the annular space is heated by the hot hydrocarbon fluids, the trapped fluid will expand. In some instances, this expansion can collapse the inner casing, thereby making future mitigation of the well more problematic. In this situation, presence of the valve assemblies 300 and 700 allow the inner casing to bleed the pressure caused by the heat expansion. As a result, easier methods such as a capping stack can be used to get the well under control again.

In one or more embodiments described herein, the valve assembly is configured to open at a predetermined pressure differential, thereby to preventing burst or collapse of the casings and/or tubular members.

In one embodiment, the valve assembly includes a tubular body having a port for fluid communication between an exterior of the tubular body and an interior of the tubular body; a chamber formed in a wall of the tubular body, the chamber in fluid communication with the port; a closure member disposed in the chamber and configured to control fluid communication through the port in response to a pressure differential; and a retaining member coupled to the closure member for retaining the closure member in an open position.

In one or more of the embodiments described herein, the valve assembly includes a biasing member for biasing the closure member in a closed position.

In one or more of the embodiments described herein, the valve assembly may include a plug disposed on an end opposite the closure member.

In one or more of the embodiments described herein, the activation force of the closure member is adjustable. In one or more of the embodiments described herein, the activation force may be adjusted by changing a location of the plug. In another embodiment, the activation force may be adjusted by changing a length of the piston.

In one or more of the embodiments described herein, the retaining member is configured to retain the closure member in the open position until reaching a predetermined differential pressure between the exterior and the interior of the valve assembly.

In one or more of the embodiments described herein, the retaining member is configured to engage a wall of the chamber to retain the closure member in the open position.

In one or more of the embodiments described herein, the retaining member is selected from the group consisting of a collet, an o-ring, a snap ring, and combinations thereof.

In another embodiment, a method of operating a valve assembly includes coupling a valve assembly to a casing and the valve assembly having a tubular body having a port for fluid communication between an exterior of the valve assembly and an interior of the valve assembly; a chamber formed in a wall of the tubular body, the chamber in fluid communication with the port; a closure member disposed in the chamber and configured to control fluid communication through the port; and a retaining member coupled to the closure member for retaining the closure member in an open position. The method further includes opening the valve assembly in response to a predetermined pressure differential between the exterior and the interior of the valve assembly, and retaining the closure member in the open position.

In one or more of the embodiments described herein, the method further includes closing the valve assembly in response to a second predetermined pressure differential.

In one or more of the embodiments described herein, the predetermined pressure differential to open the valve assembly is different from the second predetermined pressure differential to close the valve assembly.

In one or more of the embodiments described herein, the method further includes repeatedly opening and closing the valve assembly in response to respective predetermined pressure differentials.

In one or more of the embodiments described herein, a second pressure differential to close the port is smaller than the predetermined pressure differential.

In one or more of the embodiments described herein, a net force acting on the closure member is sufficient to release the retainer member.

While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 

1. A valve assembly, comprising: a tubular body having a port for fluid communication between an exterior of the tubular body and an interior of the tubular body; a chamber formed in a wall of the tubular body, the chamber in fluid communication with the port; a closure member disposed in the chamber and configured to allow fluid communication through the port in response to a predetermined pressure differential; and a retaining member coupled to the closure member for retaining the closure member in an open position.
 2. The valve assembly of claim 1, wherein the retaining member is configured to engage a wall of the chamber to retain the closure member in the open position.
 3. The valve assembly of claim 1, further comprising a biasing member for biasing the closure member in a closed position.
 4. The valve assembly of claim 3, wherein the biasing member is disposed between the closure member and a plug.
 5. The valve assembly of claim 1, wherein the closure member comprises a piston.
 6. The valve assembly of claim 1, wherein a second pressure differential to close the port is smaller than the predetermined pressure differential.
 7. The valve assembly of claim 1, wherein the retainer member is expandable.
 8. The valve assembly of claim 1, wherein the retaining member is selected from the group consisting of a collet, an o-ring, a snap ring, and combinations thereof.
 9. The valve assembly of claim 1, wherein an activation force of the closure member is adjustable.
 10. The valve assembly of claim 9, wherein the activation force is adjusted by changing a location of a plug disposed on an end opposite the closure member.
 11. The valve assembly of claim 9, wherein the activation force is adjusted by changing a length of the closure member.
 12. The valve assembly of claim 1, wherein the closure member includes a sealing member configured to seal the port.
 13. The valve assembly of claim 12, wherein the closure member further comprises a second sealing member for engaging the chamber.
 14. The valve assembly of claim 13, further comprising a plug having a third sealing member for engaging the chamber.
 15. The valve assembly of claim 14, further comprising a biasing member disposed between the closure member and a plug.
 16. The valve assembly of claim 15, wherein the biasing member is disposed between the second sealing member and the third sealing member.
 17. The valve assembly of claim 1, wherein the retainer member is configured to allow the closure member to close the port when a pressure differential is below the predetermined pressure differential.
 18. A method of controlling fluid communication through a port, comprising: closing the port using a closure member movable in a chamber; opening the port at a predetermined pressure differential, wherein the closure member moves from a closed position to an open position; retaining the closure member in the open position using a retainer member; and moving the closure member to the closed position when a pressure differential is below the predetermined pressure differential, thereby closing the port.
 19. The method of claim 18, wherein the retainer member is movable with the closure member.
 20. The method of claim 18, wherein retaining the closure member in the open position comprises engaging the retainer member with a shoulder in the chamber.
 21. The method of claim 18, wherein closing the port comprises biasing the closure member in the closed position using a biasing member.
 22. The method of claim 18, wherein a first fluid pressure is applied to the closure member to open the port is larger than a second fluid pressure acting on the closure member to close the port.
 23. The method of claim 18, wherein a net force acting on the closure member is sufficient to release the retainer member.
 24. A method of operating a valve assembly, comprising: coupling a valve assembly to a casing, the valve assembly having: a tubular body having a port for fluid communication between an exterior of the tubular body and an interior of the tubular body; a chamber in fluid communication with the port; and a closure member disposed in the chamber and configured to control fluid communication through the port; opening the port in response to a predetermined pressure differential between the exterior and the interior of the tubular body, and retaining the closure member in the open position using a retaining member. 